Blockchain or block chain is the new fashionable "thing" in digital banking. Blockchain has been strictly connected to Bitcoins as it has been the technological basis for Bitcoins transactions. It consists of blocks of data holding batches of individual financial transactions forming a sort of a public ledger. Investment banks are getting extremely excited by the prospective and potential use of this technology for tracking and clearing financial transactions as a genuine replacement for clearing and settlement systems currently in use. After the big legal issue on whether Bitcoins could be considered a currency, it looks like that we are already in for a new legal challenge to identify and regulate something the shape and the implications of which are not completely defined yet.